1. 环境的需求(这里虚拟机下Centos6的安装就不说了)
          Centos6 + hadoop-0.21.0.tar
2. 服务器的配置(我在这里均为2个CPU,2G内存,100硬盘)
   在这里,服务器IP最好是固定的,也就是说,能相互之间用ping命令ping通的IP
   建议在公司开发,因为公司有这个条件,我在这里配置了三台datanode,分别为
   Datanode1,Datanode2,Datanode3(这些都是创建虚机的主机名)
          服务器名称     IP地址(自己定)
   Namenode       192.168.16.1
   Datanode1                            192.168.16.2
   Datanode2                            192.168.16.3
   Datanode3                            192.168.16.4
   2.1 修改服务器IP的方法如下:
                            vi  /etc/sysconfig/network-scripts/ifcfg-eth0
                            
                            DEVICE="eth0"
                            #这里是你网卡的物理地址,通常检测到的网卡你就不用输入了
                            #打开后该项已经存在,无需修改
                            HWADDR="00:0C:29:95:1D:A5"
                            BOOTPROTO="static"
                            ONBOOT="yes"
                            #这里是IP地址,不能重复,从253降序排列,被占用了的不能再次使用.
                            IPADDR=172.16.101.245
                            NETMASK=255.255.255.0
                            NETWORK=172.16.101.0
                            BROADCAST=172.16.101.255
                            GATEWAY=172.16.101.254
 
                            退出保存后,执行如下命令,使设置的网关马上生效:
                            shell>> ifdown eth0
                            shell>> ifup eth0
                            shell>> /etc/init.d/network restart
3. 安装JDK6(我用的是jdk-6u26-linux-x64-rpm.bin)
        3.1. 创建安装目录 mkdir /usr/java/
        3.2. 把jdk-6u26-linux-x64-rpm.bin移动到/usr/java/下然后执行
                          ./jdk-6u26-linux-x64-rpm.bin
                          运行中会要求输入,顺序yes和按回车就行.
                          执行后会看到一个文件夹名为:jdk1.6.0_26
        3.3. 设置环境变量
                            /etc/profile增加如下内容 
                            #config java
                            JAVA_HOME=/usr/java/jdk1.6.0_26
                            CLASSPATH=.:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/lib/dt.jar
                            PATH=$JAVA_HOME/bin:$HOME/bin:$PATH
                            export PATH JAVA_HOME CLASSPATH
        3.4. 让设置生效: source /etc/profile
4. 安装ssh服务器和客户端
        a. yum search ssh
        b. 找到要安装的server(这里拿openssh-server.x86_64)
        c. 安装server: yum install openssh-server.x86_64
        d. 安装client(这里拿openssh-clients.x86_64)
        e. 安装client: yum install openssh-clients.x86_64
5. 设置ssh进行Namenode和Datanode之间无密码访问
        a. 用 ssh-key-gen 在本地主机上创建公钥和密钥
                            [root@Namenode ~]# ssh-keygen -t  rsa
                            Enter file in which to save the key (/home/jsmith/.ssh/id_rsa):[Enter key] 
                            Enter passphrase (empty for no passphrase): [Press enter key]
                            Enter same passphrase again: [Pess enter key]
                            Your identification has been saved in /home/jsmith/.ssh/id_rsa.
                            Your public key has been saved in /home/jsmith/.ssh/id_rsa.pub. 
                            The key fingerprint is: 33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9 
                            root@Namenode
        b. 用 ssh-copy-id 把公钥复制到远程主机上
                            [root@Namenode ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub  root@Datanode1
                            root@Datanode1's password:
                            Now try logging into the machine, with ―ssh ?root@Datanode1‘‖, and check in: 
                            .ssh/authorized_keys to make sure we haven‘t added extra keys that you weren‘t expecting.
                            [注: ssh-copy-id 把密钥追加到远程主机的 .ssh/authorized_key 上.]
   c. 直接登录远程主机
                            [root@Namenode ~]# ssh Datanode1
                            Last login: Sun Nov 16 17:22:33 2008 from 192.168.1.2 
                            [注: SSH 不会询问密码.] 
                            [root@Datanode1 ~]
                            [注: 你现在已经登录到了远程主机上]
   d. 注意:在这里,执行都在Namenode上面,而且Namenode也需要对自己进行无密码操作即
      [root@Namenode ~]# ssh-copy-id -i ~/.ssh/id_rsa.pub  root@Namenode操作,
      其他的,按照a-c重复操作Datanode2和Datanode3就行了
      一定要能无密码访问,否则不能集群Hadoop一定失败.
6. 安装Hadoop(这里,每一台服务器的JDK和Hadoop安装路径都相同)
        a. 创建安装目录 mkdir /usr/local/hadoop/
        b. 解压安装文件hadoop-0.21.0.tar放入到安装目录
tar -zxvf hadoop-0.21.0.tar
        c. 设置环境变量
                            /etc/profile增加如下内容 
                            #config hadoop
                            export HADOOP_HOME=/usr/local/hadoop/
                            export PATH=$HADOOP_HOME/bin:$PATH
                            #hadoop的日志文件路径的配置
                            export HADOOP_LOG_DIR=${HADOOP_HOME}/logs
               让设置生效: source /etc/profile
        d. 设置主从配置
                     Namenode中/etc/hosts的配置如下:
                     192.168.16.1        Namenode
                     192.168.16.2        Datanode1
                     192.168.16.3        Datanode2
                     192.168.16.4        Datanode3
   
                     Namenode中/usr/local/hadoop/conf/masters的配置如下:
                     Namenode
                     
                     Namenode中/usr/local/hadoop/conf/slaves的配置如下:
                     Datanode1
                     Datanode2
                     Datanode3
                     
                     
                     Datanode1中/etc/hosts的配置如下:(/usr/local/hadoop/conf/中的masters和slaves的配置跟Namenode一样)
                     192.168.16.1        Namenode
                     192.168.16.2        Datanode1
                     
                     Datanode2中/etc/hosts的配置如下:(/usr/local/hadoop/conf/中的masters和slaves的配置跟Namenode一样)
                     192.168.16.1        Namenode
                     192.168.16.3        Datanode2
                     
                     Datanode3中/etc/hosts的配置如下:(/usr/local/hadoop/conf/中的masters和slaves的配置跟Namenode一样)
                     192.168.16.1        Namenode
                     192.168.16.4        Datanode3
   e. 修改配置文件/usr/local/hadoop/conf/ hadoop-env.sh
      把JAVA_HOME该为安装jdk的路径
                            # The java implementation to use.  Required.
                            export JAVA_HOME=/usr/java/jdk1.6.0_26/
   f. 修改配置文件 core-site.xml内容如下:
                            <configuration>
                               <property>
                                 <name>fs.default.name</name>
                                 <value>hdfs://Namenode:9000/</value>
                               </property>
                              <property>
                                <name>hadoop.tmp.dir</name>
                                <value>/usr/local/hadoop/tmp/</value>
                              </property>
                            </configuration>
   g. 修改配置文件 hdfs-site.xml内容如下:
                            <configuration>
                <property>
                  <name>dfs.replication</name>
                  #设置备份文件数
                  <value>1</value>
                </property>
                            </configuration>
   h. 修改配置文件 mapred-site.xml内容如下:
                            <configuration>
                 <property>
              <name>mapred.job.tracker</name>
              #一般jobtracker和namenode设置到同一台机器上,但是同样可以集群
              <value>Namenode:9001</value>
                 </property>
                            </configuration>
   i. 注意:上面讲的配置文件全部是在Namenode中配置的,只要把这三个配置文件拷贝复制到其他的Datanode上就行了
   j. 初始化Hadoop: cd /usr/local/hadoop/
               ./bin/hadoop namenode -format
               出现类似如下的信息:但是不能出现ERORR字段.
                            .2.jar:/usr/local/hadoop/bin/../lib/paranamer-generator-2.2.jar:/usr/local/hadoop/bin/../lib/qdox-1.10.1.jar:/usr/local/hadoop/bin/../lib/servlet-api-2.5-6.1.14.jar:/usr/local/hadoop/bin/../lib/slf4j-api-1.5.11.jar:/usr/local/hadoop/bin/../lib/slf4j-log4j12-1.5.11.jar:/usr/local/hadoop/bin/../lib/xmlenc-0.52.jar:/usr/local/hadoop/bin/../lib/jsp-2.1/*.jar:/usr/local/hadoop/hdfs/bin/../conf:/usr/local/hadoop/hdfs/bin/../hadoop-hdfs-*.jar:/usr/local/hadoop/hdfs/bin/../lib/*.jar:/usr/local/hadoop/bin/../mapred/conf:/usr/local/hadoop/bin/../mapred/hadoop-mapred-*.jar:/usr/local/hadoop/bin/../mapred/lib/*.jar:/usr/local/hadoop/hdfs/bin/../hadoop-hdfs-*.jar:/usr/local/hadoop/hdfs/bin/../lib/*.jar
                            STARTUP_MSG:   build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.21 -r 985326; compiled by 'tomwhite' on Tue Aug 17 01:02:28 EDT 2010
                            ************************************************************/
                            Re-format filesystem in /usr/local/hadoop/tmp/dfs/name ? (Y or N) y
                            Format aborted in /usr/local/hadoop/tmp/dfs/name
                            11/06/16 13:04:17 INFO namenode.NameNode: SHUTDOWN_MSG: 
                            /************************************************************
                            SHUTDOWN_MSG: Shutting down NameNode at namenode/172.16.101.251
                            ************************************************************/
   k. 启动Hadoop ./bin/start-all.sh
                            This script is Deprecated. Instead use start-dfs.sh and start-mapred.sh
                            starting namenode, logging to /usr/local/hadoop//logs/hadoop-root-namenode-namenode.out
                            datanode1: starting datanode, logging to /usr/local/hadoop/bin/../logs/hadoop-root-datanode-datanode1.out
                            datanode2: starting datanode, logging to /usr/local/hadoop/bin/../logs/hadoop-root-datanode-datanode2.out
                            datanode3: starting datanode, logging to /usr/local/hadoop/bin/../logs/hadoop-root-datanode-datanode3.out
                            namenode: starting secondarynamenode, logging to /usr/local/hadoop/bin/../logs/hadoop-root-secondarynamenode-namenode.out
                            starting jobtracker, logging to /usr/local/hadoop//logs/hadoop-root-jobtracker-namenode.out
                            datanode3: starting tasktracker, logging to /usr/local/hadoop/bin/../logs/hadoop-root-tasktracker-datanode3.out
                            datanode2: starting tasktracker, logging to /usr/local/hadoop/bin/../logs/hadoop-root-tasktracker-datanode2.out
                            datanode1: starting tasktracker, logging to /usr/local/hadoop/bin/../logs/hadoop-root-tasktracker-datanode1.out
      启动后用命令JPS查看结果如下:
                            [root@namenode hadoop]# jps
                            1806 Jps
                            1368 NameNode
                            1694 JobTracker
                            1587 SecondaryNameNode
                            然后到Datanode1/2/3上去查看,执行JPS,结果如下:
                            [root@datanode2 hadoop]# jps
                            1440 Jps
                            1382 TaskTracker
                            1303 DataNode
                            [root@datanode2 hadoop]# jps
                            1382 TaskTracker
                            1303 DataNode
                            1452 Jps
                            说明你成功集群安装了Hadoop
7. HDFS操作
          运行bin/目录的hadoop命令,可以查看Haoop所有支持的操作及其用法,这里以几个简单的操作为例。
建立目录
          [root@namenode hadoop]# ./bin/hadoop  dfs  -mkdir  testdir
          在HDFS中建立一个名为testdir的目录
复制文件
          [root@namenode hadoop]# ./bin/hadoop  dfs  -put  /home/dbrg/large.zip  testfile.zip
          把本地文件large.zip拷贝到HDFS的根目录/user/dbrg/下,文件名为testfile.zip
查看现有文件
          [root@namenode hadoop]# ./bin/hadoop  dfs  -ls